Control apparatus



. Oct. 12 1926.

A. L. HARVEY ET AL CONTROL APPARATUS Filed April 16. '1923 Oscar C Cordes.

ATTORNEY Patented Oct. 12, 1926.

warren STATES PATENT OFFICE;

ALBERT L. HARVEY AND OSCAR C. CORDES, F WILKINSBURG, PENNSYLVANIA, AS- SIGNORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A COR-- PORATION OF PENNSYLVANIA.

con'rnon APPARATUS.

Application filed April 16, 1928.

Our invention relates to motor-control apparatus and it has particular relation to limit switches for the control of machine tools and similar machines.

The object of our invention is to provide a simple device for accurately controllingthe l'cedanotor of a machine-tool in accordance with various operating requirements.-

(lur invention will be best understood by reference to the accompanying drawing, in which- Figure 1 is a view, chiefly in side elevation but partially in section, of apparatus embodying our invention Fig, 2 is a view, in end elevation, of a portion of the apparatus illustrated in Fig. 1, and

Fig. 3 is a diagrammatic representation of circuits and apparatus, such as may be emv ployed according toour invention.

Referring .to the drawing, our limit switch comprises a rotatable control drum 1, which is mounted upon pedestal bearings 2 and 3, and the drum shaft 4 is preferably provided with a flexible coupling5 of a familiar type, whereby the shaft {1 may be; operatively connected to a feed-motor 6. The drum 1 comprises an insulated portion or base 7 for supporting a plurality of contact rings or segments 8, 9, 10 and 11. Stationary contact members 12 are conveniently mounted for engagement with segments 8 and 9. The segments 8 and 10, and 9 andll, respectively, are electrically connected by means of rivets 13 which also support said segments upon the insulating base 7. A ratchet-Wl'ieel 14 is loosely mounted for rotation on the shaft 4 and supports a pair of movable contact members 15 and 16 which are insulated from the ratchet wheel by means of a supporting base 17.

There is also mounted, for rotation about the shaft 4:, a rocker arm 18 which carries a reversible pawl 19 for engaging and operating the ratchet-wheel 14. The rocker arm 18 is preferably connected, by means of a link 20, to a rotary member 21 which is mounted upon, and operated by, the machine-tool mechanism.

The machine-tool mechanism may be of a familiar type comprising a rotatable shaft 252 having a definite motion for each operation of the machine-tool. In order that the movement of the rocker arm 18 may be regu- Serial No. 632,591.

lated, an adjustment is provided by means of a slotted portion in the member 'llherefore, by means of a clamping nut 21, the linkmay be adjustably iixed at a suitable radial distance, from shaft 22. Hotation of shaft 22 thus imparts a reciproratingmovement to the rocker arm 18.

In Fig, 3, we have illustrated, conventiorr ally, the feed motor 6 operatively connected to a cutting tool 25. The motor 6 and the cutting tool 25 may be carried upon'a planer bed, or other machine tool mechanism, as will be readily understood, and movement of said bed may also be transmitted to shaft 22, illustratedin Fig. ,2. Vehavo illustrated in Fig. 3, a conventional type of master switch 26, whereby certain operations of the motor 6 are controlled as hereinafter described.-

Assuming, that the drum 1 occupies the 1 position illustrated in Fig. 2, movable contact member 16 occupies an inoperative position in engagement I with an insulated portion 27 extending into-a broken portion of segment 11. Atthe completion of acutting stroke, and when a return strokeof the machine tooliis commenced,shaft 22 is rotated in a clock-wise direction, for example, making, say, one complete revolution during said return stroke and thereby actuating lever 18 to the right to a predetermined de reeand back to its illustrated position. This movement of lever 18 imparts movement to the control drum 1 to a degree corresponding to the angular movement of lever 18. Movable contact member 16, which is carried by the ratchet wheel 14, is rotated in an equal an gular amount taking up a new position in contact with segment 11. Assuming that master switch 26 has been set to make contact along the right hand row of segments, in position 1*, current is immediately supplied to the field winding 28 of feed motor 6 from the positive line ,conductor through contact member 15, segments 10 and 8, brushes 12, segments 9 and 11, contact member 16, master switch 26 and field winding 28 to the negative line conductor. Motor 6 now actuates the feeding mechanism of tool 25 in a forward direction. The operation of motor 6 returns control drum 1 to its former relative position with respect to the contact member 16. 'llheretore, it will be evident that the time of operation of the motor 6 and the feeding of the tool 25 depends upon the angular movement of control drum 1 which operates to interrupt the current supply when contact member 16 engages the insu lated drum portion 27.

If desired, the drum 1 may be operated in a counter-clockwise direction by reversing the position of the pawl 19. Master switch 26 must then be set in reverse position F. As previously indicated, the angular movement of rocker arm 18 may be varied by means of the adjustable nut 24', whereby the required amount of feed for the tool 25 is obtained.

The feed motor 6 may be operated independently of the limit switch, as is required in what is termed traversing, or for any other desirable machine operation, by actuating master switch 26 to a forward or reverse position T. It is apparent, by reference to the diagram in Fig". 3, that the oper ation of motor (3 is, under these conditions, independent of the position of control drum 1 of the limit switch. Currentis supplied directly from the positive and negative line conductors through master switch lVe do not wish to be limited to the precise illustrated form of our invention, since it is obvious that other means, such as a switch mechanism of the cam type, may readily be substituted for the drum or sliding contact arrangement herein described. It is probable that our invention will [ind application other than for the operation of m-achine-tool equipment.

\Ve claim as our invention:

1. In a machine-tool control system, a limit-switch comprising a rotatable control drum and a reversible motor therefor, means for controlling the motor, a movable contact member for engaging said drum, and a ratchet device for actuating said contact member a predetermined amount to thereby operate said motor to return said drum to its prior relative position with respect to said contact member.

2. In a machine-tool control system, a limitswitch comprising a rotatable control drum and a reversible motor therefor, reversing means for the motor, a movable contact member for engaging said drum, and a reversible ratchet device for rotating said contact member about said drum selectively in either of two directions to thereby operate said motor to return said drum to its prior relative position with respect to said contact member.

3. In a machine-tool control system, a limit-switch comprising a rotatable control drum and a reversible motor therefor, a reversing switch for the motor, a stationary contact member, a movable contact member. a rocker-arm and a reversible ratchet-pawl for actuating said movable member about said drum selectively in either of two directions to render said contact members ef fective to operate said motor and return said drum to its prior relative position with respect to said movable contact member.

In testimony whereof, we have hereunto subscribed our names this 12th day of April, 1923.

ALBERT L. HARVEY. OSCAR C. CORDES. 

